<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Dom css</title>
</head>
<body>
	<div id="main">helloworld</div>
	<script type="text/javascript">
		var main = document.getElementById("main");
		main.style.color = "blue";
		main.style.fontSize = "100px";
	</script>
</body>
</html>